Circumferentially contractible clamps are widely used to clamp pipe members or the like in an end-to-end sealed relationship. Such contractible clamps usually consist of a band or strap adapted to encircle the end flanges of the pipe members to be connected, or the band may consist of a plurality of interconnected elements. The ends of the band are interconnected by an actuator capable of drawing the ends toward each other, and the actuator often takes the form of an over-center lever assembly. In a contractible clamp using an over-center lever assembly the lever is usually pivotally mounted to one end of the band having portions releasably engagable with an anchor mounted on the other end. Operation of the lever between a latch position and an open position actuates the band ends toward and away from each other contracting and expanding the band about the end flanges of the objects being connected. Typical examples of these types of clamps are shown in U.S. Pat. Nos. 1,646,463; 3,964,774; 4,008,937 and 4,123,095.
Contractible band clamps of the aforementioned type are relatively simple to operate and may be quickly applied and removed, however, upon actuating the lever towards the open position, resilience of the band causes the lever to "swing" open uncontrollably and the clamp to fully expand rapidly releasing the connected pipe members. Often, the clamps are employed with pipe members connected under pressure, and if pressure is present during opening of the clamp, the associated pipe members could suddenly separate possibly resulting in serious injury to the operator or damage to the pipe members. Thus, there is a definite need for an over-center lever actuated clamp to have a safety feature allowing pressure, if present, to be safely released during opening of the clamp, but heretofore, an over-center lever actuated clamp provided with such a feature has not been available for use.
It is an object of the invention to provide a contractible clamp operable by an over-center lever actuator for securing a pair of conduit members together wherein the clamp is easily applied and removed, economical to manufacture, and wherein a safety retainer is provided allowing controlled release of pressure, if present, during opening of the clamp preventing a sudden separation of the conduit members.
It is another object of the invention to provide a contractible clamp operable by an over-center lever actuator for securing a pair of conduit members together having a band portion adapted to embrace the flange ends to be connected and a pivotally mounted lever movable between a latched position and an open position operatively associated with the band to facilitate contraction and expansion of the band about the flange ends, wherein a retainer assembly limits movement of the lever in the opening direction for controlling release of pressure, if present, in the event of inadvertent opening of the clamp.
In the practice of the invention the contractible safety latch clamp includes a band adapted to embrace end flanges of a pair of conduit members to be connected and an over-center lever actuator pivotally mounted upon one end of the band portion having a link pivotally mounted thereon releasably engagable with an anchor mounted on the bands other end. The band ends are displacable toward each other in association with the movement of the lever between a latch position and an open position. A U-shaped retainer bail having a pair of legs interconnected to a base is pivotally mounted to the lever and as the lever is pivoted between the latch and open positions the base of the bail slides along the outer surface of the band in the same direction as that of the lever movement. A clip is mounted to the band outer surface and has a seat portion adapted to abut with the bail base to limit movement of the lever in the opening direction. In one embodiment the clip is open at one end and as the lever moves in the opening direction the base of the bail slides through the open end and engages the seat, while in another embodiment the clip is closed trapping the base of the bail in a slot defined between the clip and the band adjacent the seat portion.
In both embodiments, opening of the clamp is accomplished by applying a lifting force on the lever in the direction of the open position necessary to overcome the tension forces maintaining the lever in the over-center latch position whereby resilience of the bands causes the lever to "swing" open. As the lever continues to "swing" the bail base slides along the band surface until it engages the clip seat causing the lever to stop in a safety release position. In the safety release position, the link maintains engagement with the anchor permitting limited separation of the band ends allowing the band to expand enough to break the seal of the connected conduit members, which is important if the clamp is used in high pressure conduit installations, whereby any pressure within the pipe members can be safely released. Removing the link out from engagement with the anchor frees the band ends with respect to each other, and the clamp can be fully expanded and removed.